Protractor



Dec. 3,. 1946. J. H. G11-:gm l 2,412,084

Filed oct. 22, 1943 |1,| l'lllllllmlm JJM, A462@ Patented Dec. 3, 1946rRo'rRAc'ro Joseph H. Gieske, St. Paul, Minn., assignor, by mesneassignments, to Niel C. Smith, Minneapolis, Minn.

Application Octoberv22, 1943, Serial No. 507342 4 Claims.

My invention relates to improvements in protractors and, moreparticularly, to a protractor of the pocket type.

The improved protractor, while intended for general use, is, due to itsnovel construction, compactness and light-weight, especially welladapted for use by persons engaged in engineering, such as chiefengineers, research engineers, tool grinders, machinists, etc., where aquickly accessible protractor is required most of the time.

The object of this invention is to provide novel means in which aturnable member and a slidable member may be simultaneously locked to abody member in diierent adjustments relative to each other and relativeto the body member.

Other objects of this invention will be apparent from the followingdescription, reference being had to the accompanying drawing, in whichlike characters indicate like parts throughout the several views.

Referring to the drawing:

Fig. l is a plan View of the improved protractor;

Fig. 2 is a fragmentary plan view, some parts being removed, other partsbeine broken away and sectioned, and still other parts sectioned on theline 2 2 of Fig. 3 on an enlarged scale; and

Figs. 3 and 4 are detail views principally in section taken on the lines3-3 and i-lI of Fig. 2, respectively.

The numeral 5 indicates a body member in the form of a flat thin bladehaving at one end an enlarged head 6. This body member 5 has a longstraight edge and a short straight edge 8 at the head 6 and which twoedges extend at right angles to each other. A scale 9 on the body member5, at its straight edge reads from the narrow end of said body member ininches and fractions thereof.

A turret ID is turnably mounted on a short tubular stud I that isperpendicular to the plane of the body member 5 and its axis, as well asthe axis of the turret I 0, is exactly the same distance from the twostraight edges 1 and 8. This stud II, which is rigidly secured to thebody member 5, extends upwardly through a hole in said body member andhas on its lower or inner end a head I2 countersunk in the under side ofthe body member 5 so that the under side of said body member 5 isperfectly smooth and will lie hat on the table or other support on whichthe protractor rests. A large thin washer I3 on the stud is interposedbetween the body member 5 and the turret I0. Formed in the outer end ofthe tubular stud II is a pair of diametrically opposite keyways I4. Inthe upper face of the turret I is an annular depression I5 thatsurrounds the stud II and is concentric therewith. Resting on the bottomof the depression I and surrounding the stud II is a thin washer I6 andon top of this washer I6 is a thicker washer I1 having keys I8 thatextend into the keyways I4 and hold the washer I1 from turning on saidstud, but is free for relative axial movement. A relatively heavy screwI9 extends into the stud I I and has threaded engagement therewith. Thisscrew I9 has a large knurled head 20, the under side of which bears onthe'washer I6 and is held `thereby spaced above and out of contact withthe turret IIJ. Obviously, by turning the screw I9 into the stud I I theturret I0 may be frictionally clamped between the body member 5 and thehead of said screw and thereby heldl from turning relative to said bodymember.

A long thin arm 2| that lies in a plane parallel to the plane of thebody member 5 is mounted for endwise sliding movement in a T-slot 22 inthe turret I0 that is eccentric to the stud It will thus be seen thatthe arm 2| is carried by the turret I0 for swinging movement about theaxis of said stud and for relative endwise adjustment. The longitudinaledges of the arm 2| are parallel and one end thereof extends at rightangles thereto and the other end thereof extends at an angle offorty-five degrees (45) to said edges. A spring member 23 in the slot 22frictionally engages one of the longitudine] edges of the arm 2| andholds the arm 2| where endwise adjusted therein.

A scale in inches and fractions thereof on the arm 2| reads from left toright. The turret I0, diametrically opposite the passageway 22, isdownwardly and outwardly beveled on an arc of a circle whose center isat the axis of said turret, as indicated at 24. Marked on the head 6,concentric with and outwardly of the beveled edge 24 on the turret I0,is a circle divided into quarters, and each quarter is graduated intoninety degrees and the graduations of said quarter read in oppositedirections from zero points as indicated at 25.

A Vernier plate 26 is mounted on the turret I0 for slightcircumferential adjustment about the axis of the stud I. This Vernierplate 26 has thereon a Vernier scale 21 that is concentric with thedegree markings 25.

To simultaneously lock, by friction, the turret I0 where adjusted withits zero point set in a predetermined position relative to the degreemarkings 25 and with the arm 2| endwise adjusted relative to saidturret, I provide a clamp actuated by a thumb screw 28 having threadedengagement with the turret IG. This clamp comprises a pointed pin 29loosely held in a hole 30 in the turret l with its point impingingagainst the head 6 eccentric to the stud |I, a ball 3l loosely held in ahole 32 in said turret l0 and resting on the arm 2 I, and a clamping bar33 resting on said pin and ball. The clamping bar 33 hasr in its underside seats 34 and 35 for the pin 29 and the ball 3|, respectively. Atthe center of each seat 34 and 35 is a small hole 36 in the clampingvbar3,3. The thumb screw 28 extends loosely through a, hole in the clampingbar 33 midway between the' seats 34 and 35, with its head impingingagainst said bar. By tightening the thumb-screw 28, the

zclamping bar 33 will be pressed onto :the pin 36 and the ball 32 andthereby force said pin lagainst the head 6 to frictionally lock theturret I 0 rela-v tive to the body member and the ball 32 will also beforced by the clamping bar 33 against the yarm 2| to frictionally locksaid arm relative to the turret ID.

It will be understood that the invention described is capable of variousmodifications within the scope of the invention herein disclosed andclaimed.

What I claim is:

1. A protractor including a body member, a turret turnably mounted onthe body member, an arm slidably mounted on the turret, two frictionmembers loosely held in holes in the turret and resting, the one on thebody member and-the other on the arm, a clamping bar resting on thefriction members, and a thumb screw extending through a hole in theclamping bar and having threaded engagement with the turret.

2. The structure dened in claim 1 further including seats in theclamping bar for the friction members.

3. A protractor including a body member, a turret turnable on the bodymember, an arm mounted in a passageway in the turret below the topthereof for endwise sliding movement eccentricyto the axis of theturret, and screw-actuated clamping means for holding the turret fromturningrelative to the body member, and extendingthrough ahole in theturret and engaging the arm for holding the same against endwise slidingmovement.

4. A protractor including a body member, a turret turnable on the bodymember, an arm mounted in a passageway in the turret below the topthereof for endwise sliding movement eccentric tothe axis of the turret,and means for holding the turret from turning relative to the bodymember and for holding the arm against endwise sliding movement relativeto the turret, said means including a clamping bar, a headed screwextending through a, hole in the clamping bar with its head engagingsaid bar for applying pressure thereto, and a member` extending througha hole in the turret, engaging the arm and actuated by the clamping bar.

JOSEPH H. GIESKE.

